WASHINGTON—More than 1,000 people have been busted at the gates of the White House the past two weeks, as the most ambitious of climate protests against Canadian oil comes to a head.

Toronto author and activist Naomi Klein was not planning to be among them. Support the cause? Sure. Speak to the anti-tarsands faithful? Absolutely. But to actually get arrested?

No, Klein and the other Canadian protesters in Washington agreed — that is a stand best left to their U.S. counterparts, who need not worry whether such close encounters with law enforcement will hamper their ability to cross borders in the future.

Yet there was Klein on Friday, being led away by police in the latest harvest of detainees after a last-second decision to put her liberty on the line in opposition to the controversial Keystone XL pipeline.